In optical configurations, such as lenses for microlithography, especially projection exposure installations for microlithography, non-rotationally symmetrical illumination or a slit-shaped image field can lead to inhomogeneous irradiation of optical elements, which in turn can lead to inhomogeneous heating of the corresponding optical element. The inhomogeneous heating can lead to corresponding distortions or stresses, which in turn can lead to changes in the optical properties of the optical element and to imaging errors.